A. Pla-Dalmau

Low-cost extruded plastic scintillator

Abstract Motivated by a need for lower cost plastic scintillation detectors, we have tested commercially available polystyrene pellets in order to produce scintillating materials that can be extruded into various shapes. Selection of the raw materials is discussed. Two techniques are described that add wavelength shifting dopants to polystyrene pellets and extrude plastic scintillating bars using these materials. Data on light yield and transmittance are presented.

Extruding plastic scintillator at Fermilab

An understanding of the costs involved in the production of plastic scintillators and the development of a less expensive material have become necessary with the prospects of building very large plastic scintillation detectors. Several factors contribute to the high cost of plastic scintillating sheets, but the principal reason is the labor-intensive nature of the manufacturing process. In order to significantly lower the costs, the current casting procedures had to be abandoned. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. This concept was tested and high quality extruded plastic scintillator was produced. The DO and MINOS experiments are already using extruded scintillator strips in their detectors. An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. This paper will discuss the characteristics of extruded plastic scintillator and its raw materials, the different manufacturing techniques and the current R&D program at Fermilab.

Development and characterization of new scintillation materials for fiber tracking and calorimetry

Abstract Several polystyrene-based scintillators have been prepared in the Chemistry Facility of Fermi National Accelerator Laboratory and their light yield, fluorescence, and transmittance have been studied. In addition, emission time distributions were measured and the decay time constants were determined. A radiation damage study was performed in which the samples were irradiated to a total dose of 10 Mrad. After annealing, the intrinsic light yield of the most radiation-hard scintillators had not changed significantly.

New fluorescent compounds for plastic scintillator applications

Abstract The fluorescent compound 3-hydroxyflavone (3HF) has been modified in order to study the resulting structure-fluorescence relationship. A series of twelve derivatives, bearing different substituents at various positions on the phenyl ring, has been synthesized. Each derivative has been tested as a dopant for plastic scintillator applications by incorporating it in a polystyrene matrix. The absorption, fluorescence, and scintillation light yield characteristics of these compounds in polystyrene have been determined. In addition, emission time distributions have been measured and decay time constants have been calculated from these data.

The MU-RAY project: detector technology and first data from Mt. Vesuvius

Muon Radiography allows to map the density of a volcanic cone. It is based on the measurement of the attenuation of the flux of muons present in the cosmic radiation on the ground. The MU-RAY project has developed an innovative detector designed for the muon radiography. The main features are the low electric power consumption, robustness and transportability, good spatial resolution and muon time of flight measurement. A 1 m2 detector prototype has been constructed. and collected data at Mt. Vesuvius for approximately 1 month in spring 2013. A second campaign of measurement has been performed at the Puy de Dome, France, in the last four months of 2013. In this article the principles of muon radiography, the MU-RAY detector and the first results from the collected data will be described.

Development of radiation hard scintillators

Substantial improvements have been made in the radiation hardness of plastic scintillators. Cylinders of scintillating materials 2.2 cm in diameter and 1 cm thick have been exposed to 10 Mrads of gamma rays at a dose rate of 1 Mrad/h in a nitrogen atmosphere. One of the formulations tested showed an immediate decrease in pulse height of only 4% and has remained stable for 12 days while annealing in air. By comparison a commercial PVT scintillator showed an immediate decrease of 58% and after 43 days of annealing in air it improved to a 14% loss. The formulated sample consisted of 70 parts by weight of Dow polystyrene, 30 pbw of pentaphenyltrimethyltrisiloxane (Dow Corning DC 705 oil), 2 pbw of p-terphenyl, 0.2 pbw of tetraphenylbutadiene, and 0.5 pbw of UVASIL299LM from Ferro.

Radiation effects in intrinsic 3HF scintillator

Abstract Test scintillators of the type 3-hydroxyflavone (3HF) plus polystyrene were prepared with 3HF doping concentrations between 0.05% and 2.0% by weight. Ternary scintillators of the type p-terphenyl(1%)+3HF(0.01%) and p-terphenyl(1%)+3HF(0.1%) in polystyrene were also prepared. The scintillation light yield is given for all samples. Representative fluorescence and transmittance spectra are also shown. Changes in light yield, transmittance, and fluorescence are shown for 60 Co irradiations with integrated doses of 10 and 30 Mrad.

Extruded plastic scintillator for MINERvA

An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. A new experiment at Fermilab is pursuing the use of extruded plastic scintillator. A new plastic scintillator strip is being tested and its properties characterized. The initial results are presented here.

Fluorescent Compounds for Plastic Scintillation Applications

Several 2-(2{prime}-hydroxyphenyl)benzothiazole, -benzoxazole, and -benzimidazole derivatives have been prepared. Transmittance, fluorescence, light yield, and decay time characteristics of these compounds have been studied in a polystyrene matrix and evaluated for use in plastic scintillation detectors. Radiation damage studies utilizing a {sup 60}C source have also been performed.

Radiation damage to 2-(2′-hydroxyphenyl)benzothiazoles

Abstract The fluorescent organic compound 2-(2′-hydroxyphenyl)benzothiazole (HBT) has been modified by substitution at various positions of the phenyl ring in order to increase its quantum yield. Each derivative has been tested as a dopant in a polystyrene matrix for plastic scintillator applications. The transmittance, fluorescence, scintillation light yield, and radiation damage characteristics of these compounds in polystyrene have been determined. In addition, a comparative study of the HBT derivatives and 3-hydroxyflavone (3HF) has been performed. Only samples doped with the 4CNHBT derivative exhibit light yield and radiation resistance similar to those doped with 3HF.